A field emission device emit electrons in response to an applied electrostatic field. Such devices be useful in a wide variety of applications including displays, electron guns and electron be lithography. A particularly promising application is the use of field emission devices in addressable ways to be flat panel displays. See, for example, the December 1991 issue of Semiconductor International, p. 11; C. A. Spindt et al., IEEE Transactions on Electron Devices, Vol. 38 (10), pp. 2355-63 (1991); and J. A. Costellano, Handbook of Display Technology, Academic Press, New York, pp. 254-57 (1992), all of which are incorporated herein by reference.
A typical field emission device comprises a cathode including a plurality of field emitter tips and an anode spaced from the cathode. A voltage applied between the anode and cathode induces the emission of electrons towards the anode.
Conventional electron emission flat panel displays typically comprise a flat vacuum cell having a matrix tray of microscopic field emitters tips formed on a cathode of the cell ("the back plate") and a phosphor-coated anode on a transparent front plate. Between cathode and anode is a conductive element called a "grid" or "gate". The cathodes and gates be typically intersecting slips (usually perpendicular slips) whose intersections define pixels for the display. A given pixel is activated by applying voltage between the cathode conductor slip and the gate conductor strip whose intersection defines the pixel. A more positive voltage is applied to the anode in order to improve a relatively high energy (400-1000 eV) to be emitted electrons. See, for example, U.S. Pat. Nos. 4,940,916; 5,129,850; 5,138,237; and 5,283,500, each of which is incorporated herein by reference.
Diamonds are desirable field emitters. Early field emitters were largely sharp-tipped structures of metal or semiconductor, such as Mo or Si cones. Such tips, however, are difficult to make, have insufficient durability for many applications and require a high voltage (about 100 V) to induce electron emission. Diamonds, however, have structural durability and can have negative electron affinity--properties that make them at&active for field emission devices. Field emission devices employing diamond field emitters are disclosed, for example, in U.S. Pat. Nos. 5,129,850 and 5,138,237 and in Okano et al, Appl. Phys. Lett., Vol. 64, p. 2742 et seq. (1994), all of which are incorporated herein by reference. Flat panel displays which can employ diamond emitters are disclosed in co-pending Jin et al U.S. patent applications Ser. No. 08/299,674 and U.S. application Ser. No. 08/299,470, now U.S. Pat. No. 5,504,385 both filed Aug. 31, 1994, which are incorporated herein by reference.
Enhanced diamond emitters grown or treated to increase the concentration of defects and thereby enhance their low voltage emission are described in the concurrently-filed, co-pending U.S. patent application Ser. No. 08/331,458 of Jin et al entitled "Field Emission Devices Employing Enhanced Diamond Field Emitters." Defect-rich diamond material characterized by a broadened diamond peak at 1332 cm.sup.-1 in Raman spectroscopy with a full width at half maximum (FWHM) in the range 5-15 cm.sup.-1 can emit electrons in current density of at least 0.1 mMmm.sup.2 at a low applied field of 25 V/.mu.m or less.